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RCraddock 02-01-2021 10:11 PM

Not so much a drop in as the mixture cable is a bit different and typically uses a Bowden cable style attachment if memory serves.

echostar7 03-03-2021 10:02 AM

I think one thing being overlooked about the tbi being a drop in replacement are the requirements for fuel filtration. the TBI requires a fuel filter of 40 micron or finer to be installed to protect the TBI and the last chance needle filter is not good enough. where are you going to install a 40 micron filter?

painless 03-03-2021 04:29 PM

Also, there is a primer button that needs either a cable or a servo to actuate.

Snowflake 03-04-2021 07:41 AM


Originally Posted by 00Dan (Post 1489806)
Are these units a fairly straight drop-in replacement for a carb or would airbox and cowl modifications typically be required?

Airbox and cowl, no. But your throttle/mixture cables will change as the actuation geometry is different. Also, as mentioned, you'll need a cable or servo (and possibly some mechanical linkage bits) to actuate the priming button.

RV7 To Go 03-04-2021 08:46 PM


Originally Posted by 00Dan (Post 1499435)
Still wondering in this. I may need to change carbs and for the price the rotec is an attractive option.

Not an easy change. Rotec now recommends a fuel return line and an air/fuel ratio gauge for setting it up. As mentioned the primer cable, prefilter requirements and linkage changes.

Can't speak to the O-320 size but the O-360 size is about 1.5" shorter in height than the MS carb. I tried one for about 100hrs on my 360 after doing some of the mods Rockett Bob used (1/4" insulator at the sump, 1.5"x 6" dia. plenum adapter on the inlet...Bob used a straight Venturi style adapter, A/F gauge, drilled out a few of the spraybar holes at the WOT end). Never did put in a return line but did not have an issue with hot starting. The engine ran smooth, started and idled great but ran lean at WOT. I got tired of messing with it and changed to the MS. Now have 2 of them gathering dust in the hangar. (Paul gave me a good deal on the second one which was supposed to be the solution...ran worse than the first one - never flew it) Very poor support unless I was spending money. I have read that some people have had better experiences with the O-320 size. I personally know one person that replaced his Rotec radial using the TBI with a carbed Lycoming on his new Hatz Biplane after having 3 engine failures. He also received no support.

My opinion, based on my experience is buyer beware.

Feel free to send a PM if you would like more details.

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